Cling film, also known as static cling film, is applied to windows and smooth surfaces for temporary use as signage or other functional applications such as sun shade films. The natural adhesion of the smooth flexible film can provide sufficient holding power while still allowing easy removal. During application, the contact of the film surface with substrate results in instantaneous adhesion. Attempts to achieve uniform contact over the entire smooth surface often result in entrapment of air bubbles and large air pockets, which are not easily pressed out.
Anyone who has ever attempted to hang wallpaper can appreciate the frustration that can arise when entrapped air beneath a film can not be removed easily. The most common solutions to this problem are to remove and reapply the film or to perforate the film to release the entrapped air. Multiple attempts to adhere the same film to a substrate can compromise its appearance or increase the probability of uneven or misaligned film on the substrate. Perforating a film mars its appearance. The removal of air bubbles is also labor intensive.
For cling films, prior common solutions to this problem are to remove and reapply the film, which can contaminate the film. Any attempt to press out some of the air bubbles usually has limited effectiveness. Another solution to the problem is to wet the substrate or the film before application, which tends to cause the film to slide on vertical surfaces even if the messiness of the application is deemed acceptable. One might think that a substrate can be textured to permit egress of fluids during film application, but that textured surface may not have enough contact area for the cling film to cling for the desired period of time. So, there are no good solutions to this problem in the art.